setting an array element with sequence. The reqsted array has an inhomogenous shape after 1 dimnsions.The detectd shap was (1812,) +inhomogeneous part

Question

I'm using 2 datasets.

1. sst dataset, for which the code is working completely fine.
2. but, when I use the same code for the books dataset(taken from amazon), I'm getting the error.

def make_idx_data_cv(revs, word_idx_map, cv, max_l=51, k=300, filter_h=5):
    """
    Transforms sentences into a 2-d matrix.
    """
    train, test = [], []
    for rev in revs:
        sent = get_idx_from_sent(rev["text"], word_idx_map, max_l, k, filter_h)   
        sent.append(rev["y"])
        if rev["split"]==cv:            
            test.append(sent)        
        else:  
            train.append(sent)   
    train = np.array(train,dtype="int")
    test = np.array(test,dtype="int")
    return [train, test]